[llvm-commits] [llvm] r122627 - /llvm/trunk/lib/CodeGen/StrongPHIElimination.cpp

[Cameron Zwarich]

On Dec 29, 2010, at 6:39 PM, Jakob Stoklund Olesen <stoklund at 2pi.dk> wrote:

> On Dec 29, 2010, at 4:36 PM, Cameron Zwarich wrote:
>>> How does strong phi elimination affect the runtime of coalescing?
>> 
>> It doesn't reduce it as much as I would like. On 403.gcc, coalescing takes up 4.0-4.1% of compile time with normal PHIElimination, and it goes down to 3.9% with StrongPHIElimination. StrongPHIElimination is getting fast enough that total compile time is just noise, but I'd like to investigate why there isn't as much of a speedup in coalescing as I would expect.
> 
> You may want to get some numbers from the ARM target as well. X86 has lots of copies from two-address instructions.

How useful would this sort of dominator-based coalescing be for copies introduced by two-address instructions?

Cameron
> 
>> 
>>